GDI+ application: write text over existing one

Question

Hello In my GDI+ application I need to change dynamically some texts. If just write new string over existing one 2 strings will be superposed. So one should to remove old string before to write the new one. Only solution I found for the moment is to invalidate the specific region of the control where graphics are drawn (Panel in my case). It works perfectly - after applying pnl_Graphics.Invalidate(rect1)  all graphics inside of rect1 disappear. But when I draw new text in the same region it doesn't appear ! What could be a workaround ? Thanks in advance. Pavel.

Pavel · Answer

I lloked through some examples when graphics are drawn inside of Paint event handlers. All have fixed code - i.e. when invoked they do the same job. In my case the fashion of how redraw a panel (or rather region of panel) depends on algoritm. So coding of Paint event cannot be rigid. If my understandig is correct if one need to redraw a Control (e.g. Panel) he should call Invalidate method (optionally with limits) - pnl.Invalidate() ; Invalidate calls Paint event that has following interface: private void pnl_Paint(object sender PaintEventArgs e) How to pass some parameters in order to pnl_Paint know what to do ? Is there some other workaround - without using of Paint handler ?

Pavel · Answer

Hi Manesh Thanks for response. There is no any event for redrawing. Until I've met this problem I don't need it. I drawn all my graphics using dc.DrawRectangle  dc.DrawEllips  dc.DrawString  etc. (where dc - Graphics object associated with Panel ) and all objects are drawn perfectly. Regards.

Mahesh Chand · Answer

What even of Form are you using the redraw the text? It must be Form's paint or any control's paint event. If you are drawing on a button click or some other events you must force the paint method execution.